Soybean Biodiesel Research Articles

Creating a harmonized time series of environmentally-extended input-output tables to assess the evolution of the US bioeconomy - A retrospective analysis of corn ethanol and soybean biodiesel

Expanding the domestic bioeconomy can help diversify the use of national resources and reduce emissions. Evaluating the sustainability of a growing bioeconomy, however, is inherently complex since it spans several sectors and supply chains. It requires a comprehensive, integrated analysis framework to assess the developments across the traditional sustainability dimensions. Further, the assessment of bioeconomy developments requires a robust baseline of historic data and trends. In this paper, we analyze the evolution of the biofuel portion of the US bioeconomy, focusing on two fuels that had an exponential growth in the last two decades: corn ethanol and soybean biodiesel. For this purpose, we created a novel time series of harmonized environmentally-extended input-output (EEIO) tables based on a publicly available model from the US Environmental Protection Agency and expanded its disaggregation to reflect the main supply chains of the biofuels sectors. The EEIO time series provides the historical evolution of these biofuels relative to the rest of the economy as well as on an energy-unit basis. We find that, except for energy use, the broader US economy declined in both resource intensity and most environmental impacts when normalized per one million dollars of gross domestic product. Deviating from this trend are freshwater ecotoxicity and human toxicity, mainly attributable to the expansion of commodity crops and the increase of domestic oil and gas extraction respectively. We also find that the biofuel industry's total socioeconomic, resource use and environmental impacts grew with their production increases over time. However, the industry's maturation and scale-up, combined with higher feedstock yields, contributed to a reduction of most impacts on an energy-unit basis over time.

Crystallization of hydrogenated biodiesel–ethanol–diesel blend based on the solid–liquid equilibrium theory

AbstractHydrogenated biodiesel–ethanol–diesel is a novel ternary fuel blend containing easily volatile, moderately volatile, and hardly volatile components. In this study, based on the thermodynamic phase equilibrium, a model was established to depict the phase transition under changeable pressure and temperature conditions. The crystallization behavior of hydrogenated biodiesel–ethanol–diesel ternary blends was estimated, and the influence of ethanol on the low temperature performance of ternary blends was interpreted in contrast to that of hydrogenated biodiesel–diesel binary blends. It was revealed that the crystallization points of ternary blends such as PHC5E5 (5% partially hydrogenated cottonseed biodiesel + 5% ethanol + 90% diesel), PHC10E10 (10% partially hydrogenated cottonseed biodiesel + 10% ethanol + 80% diesel), and PHC15E15 (15% partially hydrogenated cottonseed biodiesel + 15% ethanol + 70% diesel) were reduced by 4.5 K, 5.7 K and 6.1 K respectively as compared with their countering binary blends. Declines of 4.3 K, 5.3 K and 6.1 K in crystallization points were also demonstrated between partially hydrogenated soybean biodiesel ternary blends and binary blends. Meanwhile, apparent drops in crystallization quantities were perceived between ternary blends and binary blends under different temperatures. The role of ethanol affecting the crystallization of ternary blends was then comprehensively analyzed. At the onset of crystallization, ethanol was simultaneously precipitated in a eutectic manner with compositions of high melting point, impeding the tendency of nucleation and lagging the growth of solid crystals. In addition, most of non‐crystallized ethanol distributed in liquid fuel as well as the interstices of the network and the plate crystal. It beneficially increased the solubility of the crystalline composition in the base liquid to some extent. That is to say, the crystallization points and crystallization quantities were evaluated based on the solid–liquid equilibrium theory, which can provide an effective and reliable method for optimizing the low temperature performance of hydrogenated biodiesel.

Study of selective hydrogenation of biodiesel in a DBD plasma reactor

In order to achieve the selective hydrogenation of biodiesel at room temperature and under normal pressure, we researched the upgrading of soybean biodiesel using a dielectric-barrier discharge (DBD) reaction system. Using Raney-Ni as the hydrogenation catalyst, the effects of the operating parameters on the hydrogenation depth and the selectivity of biodiesel were systematically analyzed. The results show that the polyunsaturated components in soybean methyl ester were reduced by 57.04%, and that the polyunsaturated components were hydrogenated to monounsaturated components with a selectivity of 77.75%. Based on the gas chromatography and mass spectrometry (GC-MS) test results, we established a kinetic model for biodiesel hydrogenation. A comparison of the calculated and experimental results shows that the hydrogenation of the biodiesel can be described by a quasi first-order reaction model. The calculated reaction rate constants indicate that under DBD plasma reaction conditions, the hydrogenation of biodiesel has high selectivity for the formation of monounsaturated components.

Techno‐economic feasibility analysis of engineered energycane‐based biorefinery co‐producing biodiesel and ethanol

AbstractHigh feedstock cost and low oil yields per unit of land from temperate oilseed crops limit the growth of commercial‐scale biodiesel production. Recently, highly productive crops, such as sugarcane and energycane, have been engineered to accumulate triacylglycerides (TAGs) that allow the production of far more industrial vegetable oil than previously possible. A proof‐of‐concept suggests that biodiesel production from engineered energycane will be possible. However, before making efforts for scale‐up, it is critical to understand the commercial feasibility and economic competitiveness of this process. This study performs techno‐economic analysis of a unique biorefinery processing energycane to co‐produce biodiesel and ethanol. Comprehensive process simulation models were developed for two scenarios: (i) biodiesel from TAGs and ethanol from fermentation of sugars in juice and (ii) biodiesel from TAGs and ethanol from fermentation of sugars in juice and hydrolysis of carbohydrates in bagasse. Based on the target levels, the analysis was performed for energycane containing 0%, 5%, and 7.7% TAGs (d.b.). The biodiesel from engineered energycane was found economically viable and competitive to soybean biodiesel. Although the capital investment is higher compared to the soybean biodiesel plant, the biodiesel production costs ($0.66–$0.9/L) were lower than soybean biodiesel ($0.91/L). Biorefinery‐scenario‐1 processing energycane containing 7.7% TAG produces biodiesel with profitability (IRR 7.84) slightly lower than soybean biodiesel (IRR 8.3), but yields five times of biodiesel per unit land and is self‐sustainable for energy requirements. The surplus electricity can displace fossil electricity and provide environmental benefits. Monte Carlo simulation indicated that biorefinery is profitable with a 29%–65% probability (NPV > 0) which is largely controlled by feedstock composition and biodiesel market price. It is important to note that energycane can be grown on the marginal rainfed lands in S.E. USA, where soybean would not be viable. Biodiesel from engineered energycane would therefore be complementary to soydiesel in the United States.

Investigation of the impact of injection timing and pressure on emissions characteristics and smoke/soot emissions in diesel engine fuelling with soybean fuel

Engine injection strategy and renewable fuel both can improve nitrogen oxides (NOX) and smoke/soot emissions in a common-rail compression ignition (CI) diesel engine. The effects of different postinjection (PI) timings (15, 30, and 45) after top dead center (aTDC) and injection pressures (550 and 650 bar) on pollutant emissions and smoke/soot emissions were investigated for combustion of a renewable fuel (soybean biodiesel). The results showed that the levels of carbon monoxide (CO), hydrocarbons (HCs), and NOX are reduced from the combustion of soybean biodiesel compared to the diesel fuel combustion for different injection strategy. Besides, NOX emission is clearly reduced with retarded PI timing, especially at 45°. It is found that the increasing injection pressure reduced gaseous emissions for both fuels. The combination between biodiesel fuel and injection strategy can provide meaningful improvements in pollutant emissions, as well as enhance the exhaust temperature compared to the diesel fuel. With biodiesel fueling, smoke/soot emissions were reduced from biodiesel combustion (by 19.7%) under different fuel injection timings and pressures rather than from the diesel fuel combustion (by 12.2%).

Applying quasi-isothermal thermogravimetry to determine degrees of oil conversion into biodiesel

Recent research has revealed the successful use of thermogravimetric analysis (TGA) in dynamic mode as an alternative method for determining degrees of oil conversion into biodiesel. This paper reports the results obtained with the use of TGA in quasi-isothermal mode (TGA-qISO) and with quantitative proton nuclear magnetic resonance (1H qNMR) to investigate the compositions of blends of soybean oil and biodiesels (10:0, 8:2, 6:4, 4:6, 2:8, and 0:10, m:m). Also, reported are data acquired by applying a programmed sequence of TGA-qISO and gas chromatography with flame ionization detection (GC-FID) steps to a biodiesel witness sample and samples prepared by a partner laboratory. All the biodiesels were obtained by transesterification via the methyl route using homogeneous basic catalysis. Thermogravimetric curves (TG) clearly distinguished between mass losses caused by ester volatilization and those resulting from oil thermal decomposition. Ester contents calculated by TGA-qISO proved concordant with 1H qNMR and GC-FID data, with maximum differences of around 0.5% and 1.4%, respectively.

Tuning the porosity of sulfur-resistant Pd-Pt/MCM-41 bimetallic catalysts for partial hydrogenation of soybean oil-derived biodiesel

Partial hydrogenation of soybean oil-derived fatty acid methyl esters was studied using MCM-41 mesoporous silica-supported Pd-Pt bimetallic catalysts with tunable porosity under mild reaction conditions (100 °C, 0.4 MPa H2, 4 h). This process produced partially hydrogenated fatty acid methyl esters (H-FAME) as a new type of high-quality biodiesel fuel enriched in monounsaturated fatty acid methyl esters (mono-FAME), which is a potential source for formulating high blends of biodiesel fuel with petrodiesel. MCM-41 supports with various structural properties and morphologies were synthesized by self-assembly with different amounts of ammonia solution as a mineralizing agent. Bimetallic Pd-Pt nanoparticles with a Pd/Pt atomic ratio of 4 were stepwise impregnated on three MCM-41 supports, resulting in a series of Pd-Pt/MCM-41 bimetallic catalysts with tunable porosity (0.89–1.79 cm3 g−1), average pore size (3.2–8.5 nm), and particle size (0.12–0.62 μm). The Pd-Pt/MCM-41 catalyst prepared with the least amount of ammonia produced the best partial hydrogenation conversion of polyunsaturated FAME into mono-FAME, ascribed to nano-aggregation resulting in a dual-pore system containing large pores for fast molecular diffusion; a high turnover frequency (1920 h−1), larger k1 rate constant (0.60 gcat−1h−1), and smaller k2 rate constant (0.37 gcat−1h−1) were obtained. Furthermore, this Pd-Pt/MCM-41 catalyst exhibited excellent sulfur resistance in the synthesis of H-FAME, even though the feedstocks contained approximately 5 ppm of sulfur contaminates. These results demonstrate that the sulfur-resistant Pd-Pt/MCM-41 bimetallic catalysts with stable and dual pore system are beneficial for obtaining higher quality BDF to reduce our reliance on fossil fuels.

Soybean biodiesel production using synergistic CaO/Ag nano catalyst: Process optimization, kinetic study, and economic evaluation

A heterogeneous CaO/Ag nano catalyst was developed and applied for biodiesel production from transesterification of soybean oil. The silver performed synergistic effects with CaO on promoting biodiesel production. The CaO/Ag nano catalysts exhibited abundant strong basic sites with larger BET surface area (7.02 vs 2.05 m2/g), pore diameter (58.84 vs 37.08 nm) and pore volume (0.070 vs 0.016 cm3/g), which significantly reduced mass transfer resistance of triglycerides during transesterification and improved the mass transfer constants. Response surface methodology was applied to investigate the influence reaction parameters and optimize biodiesel yield. A maximized biodiesel yield of 90.95 ± 2.56 % was achieved using methanol:oil molar ratio of 13, CaO/Ag loading of 5%, reaction time of 90 min and reaction temperature of 72℃. The optimized biodiesel yield for CaO catalyzed transesterification was 88.40 ± 3.34 %, using similar reaction conditions but with 180 min of reaction time. Both nano catalysts were consecutively reused for five times. Kinetic and thermodynamic studies of CaO and CaO/Ag catalyzed transesterification were performed and compared. Economic evaluation of biodiesel production using CaO and CaO/Ag was performed and compared to provide insights for heterogeneous catalyst application for biodiesel production on industrial scale.

Economic perspective of ethanol and biodiesel coproduction from industrial hemp

In this study, the economics of producing biofuels from an industrial hemp (Cannabis sativa) genotype – 19m96136 was investigated. A lignocellulosic biofuel plant, hourly consuming 85 metric tons of hemp biomass was modeled in SuperPro Designer®. The integrated bioenergy plant produced hemp biodiesel and bioethanol from lipids and carbohydrates, respectively. The structural composition of the industrial hemp plant was analyzed in a previous study. The data obtained was used to simulate feedstock composition in SuperPro Designer®.The simulation results indicated that Hemp containing 2% lipids can yield up to 3.95 million gallons of biodiesel annually. On improving biomass lipid content to 5 and 10%, biodiesel production increased to 9.88 and 19.91 million gallons, respectively. The breakeven unit production cost of hemp biodiesel with 2, 5, and 10% lipid containing hemp was $18.49, $7.87, and $4.13/gallon, respectively. The biodiesel unit production cost when utilizing 10% lipid-containing hemp was comparable to soybean biodiesel at $4.13/gallon. Furthermore, sensitivity analysis revealed the possibility of a 7.80% reduction in unit production cost upon a 10% reduction in hemp feedstock cost. Furthermore, industrial hemp was capable of producing between 307.80 and 325.82 gallons of total biofuels per hectare of agricultural land than soybean.

Spatially variable hydrologic impact and biomass production tradeoffs associated with Eucalyptus (E. grandis) cultivation for biofuel production in Entre Rios, Argentina

AbstractClimate change and energy security promote using renewable sources of energy such as biofuels. High woody biomass production achieved from short‐rotation intensive plantations is a strategy that is increasing in many parts of the world. However, broad expansion of bioenergy feedstock production may have significant environmental consequences. This study investigates the watershed‐scale hydrological impacts of Eucalyptus (E. grandis) plantations for energy production in a humid subtropical watershed in Entre Rios province, Argentina. A Soil and Water Assessment Tool (SWAT) model was calibrated and validated for streamflow, leaf area index (LAI), and biomass production cycles. The model was used to simulate various Eucalyptus plantation scenarios that followed physically based rules for land use conversion (in various extents and locations in the watershed) to study hydrological effects, biomass production, and the green water footprint of energy production. SWAT simulations indicated that the most limiting factor for plant growth was shallow soils causing seasonal water stress. This resulted in a wide range of biomass productivity throughout the watershed. An optimization algorithm was developed to find the best location for Eucalyptus development regarding highest productivity with least water impact. E. grandis plantations had higher evapotranspiration rates compared to existing terrestrial land cover classes; therefore, intensive land use conversion to E. grandis caused a decline in streamflow, with January through March being the most affected months. October was the least‐affected month hydrologically, since high rainfall rates overcame the canopy interception and higher ET rates of E. grandis in this month. Results indicate that, on average, producing 1 kg of biomass in this region uses 0.8 m3 of water, and the green water footprint of producing 1 m3 fuel is approximately 2150 m3 water, or 57 m3 water per GJ of energy, which is lower than reported values for wood‐based ethanol, sugar cane ethanol, and soybean biodiesel.

Influence of Silica Nano-Additives on Performance and Emission Characteristics of Soybean Biodiesel Fuelled Diesel Engine

The present study examines the effect of silicon dioxide (SiO2) nano-additives on the performance and emission characteristics of a diesel engine fuelled with soybean biodiesel. Soybean biofuel was prepared using the transesterification process. The morphology of nano-additives was studied using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The Ultrasonication process was used for the homogeneous blending of nano-additives with biodiesel, while surfactant was used for the stabilisation of nano-additives. The physicochemical properties of pure and blended fuel samples were measured as per ASTM standards. The performance and emissions characteristics of different fuel samples were measured at different loading conditions. It was found that the brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) increased by 3.48–6.39% and 5.81–9.88%, respectively, with the addition of SiO2 nano-additives. The carbon monoxide (CO), hydrocarbon (HC) and smoke emissions for nano-additive added blends were decreased by 1.9–17.5%, 20.56–27.5% and 10.16–23.54% compared to SBME25 fuel blends.

Vegetable tannins-based additive as antioxidant for biodiesel

The development of more sustainable antioxidants alternatives for the improvement of biodiesel oxidation stability is gaining importance. Vegetable tannins are known for their antioxidant properties. In this work, acacia (Acacia mearnsii), chestnut (Castanea sativa) and quebracho (Schinopsis lorentzii) tannins extracts were used in mixture with triethanolamine as antioxidants for soybean biodiesel. Tannins were characterized by Folin-Ciocalteau method for the determination of total phenolic content (TPC) and against DPPH (1,1-diphenyl-2-picryl-hydracyl) radical for scavenging capacity. When applied to the biodiesel at a concentration of 350 mg L−1 in mixture with 1.59 %wt of triethanolamine, tannins were highly effective in enhancing oxidative stability with superior performance than synthetic antioxidant tert-Butylhydroquinone (TBHQ). These findings indicate that vegetal tannins can be used as a renewable alternative to enhance biodiesel oxidation stability.

Study of performance parameters and emissions of four stroke CI engine using solketal-biodiesel blends

Evaluation of performance parameters, emission and brake specific fuel consumption (BSFC) were made for different blends of solketal in soybean biodiesel with 9%, 10%, 12%, 15% of solketal (volume to volume). These experiments were performed on a single-cylinder water-cooled diesel engine at different speeds and 50% load conditions. In comparison to pure diesel, it was observed that soybean biodiesel and its blends with solketal were higher BSFC. On the addition of solketal to biodiesel higher oxides of nitrogen (NOx) and carbon dioxide (CO2) emissions were reported for all the blends. total hydro carbon (THC) and carbon mono-oxide (CO) emissions were found lower for soybean biodiesel and it’s all four blends as compared to pure diesel and further decreases with the increase in solketal percentage in a blend. A decrease in CO and THC emissions were also observed with the increase in percentage of Solketal fuels. Solketel was found suitable and as an effective additive for biodiesel blends.

Effect of Natural Substances as Antioxidants and as Corrosion Inhibitors of Carbon Steel on Soybean Biodiesel

The use of natural additives in biodiesel has been investigated, however, there is limited information in the literature in relation to their influence on corrosion resistance and oxidative stability. This work aims to investigate the oxidative stability of biodiesel and the corrosion resistance of carbon steel (AISI 1020) in contact with soybean biodiesel solutions (B100) in the presence and absence of natural additives such as: rosmarinic acid, curcumin, gingerol, eugenol, thymol and quercetin. Corrosion and microscopy tests were used to assess corrosion resistance. The Rancimat technique was used to study oxidative stability. The results obtained indicate that curcumin was the best additive in relation to oxidative stability, while rosmarinic acid showed better performance in inhibiting corrosion. The effect of these substances is related to the presence of phenolic compounds or the existence of oxygen in its molecular structure.

Terpene Resin Prepared from Renewable Turpentine Oil as a New Type of Cold Flow Improver for Soybean Biodiesel / Diesel Blends

Terpene Resin Prepared from Renewable Turpentine Oil as a New Type of Cold Flow Improver for Soybean Biodiesel / Diesel Blends

Effect of poly(ethylene-vinyl acetate) pour point depressant on the cold flow properties and crystallization behavior of soybean biodiesel blends fuel.

Although biodiesel-diesel blends are being widely used in diesel engines, investigations on its cold flow properties and crystallization behavior are still scarce. In this paper, poly(ethylene-vinyl acetate) (PEVA) pour point depressant and petroleum diesel were worked together to enhance the cold flow properties of soybean biodiesel. PEVA presented a better positive effect in reducing the cold filter plugging point (CFPP) of biodiesel blends. B40 treated with 1% PEVA exerted the best cold flow properties, and its CFPP was decreased by -14 °C. In addition, the crystallization behavior was changed variously. The sizes of crystals were decreased as well as the number of crystals was increased notably.

Análisis de las prestaciones de un motor de combustión interna alternativo usando biocombustibles: (i) aceite de soya; (ii) aceite de canola

In the present study, two biofuels derived from cooking oil are evaluated. To carry out this work, an reciprocating internal combustion engine will be used, which is ready on a fully instrumented engine test bench. Firstly, the biodiesel production process is described, where soybean oil and canola oil have been used. Subsequently, the experimental section that has been used for the present investigation is described. The experimental tests are carried out: (i) modifying the degree of opening of the accelerator and (ii) using a constant load of the dynamometer. On the other hand, in the results section shows the performance of the two biofuels generated against diesel commercial. Also, in this section shows the percentage differences of: (i) engine power; (ii) mass fuel, (iii) thermal efficiency engine and, (iv) exhaust temperaturas. The tests have been carried out under different engine speed conditions of the reciprocating internal combustion engine. Where, the main average differences that have been registered in the engine test bench were: for engine power, 32 and 33%; for the mass fuel consumption of -4.5 and 5%, when using soybean biodiesel and canola biodiesel, respectively. These differences are due to the energy capacity of each biofuel and, the instantaneous evolution of combustion process inside the reciprocating internal combustion engine.

Soil acidification and impacts over microbial indicators during attenuation of soybean biodiesel (B100) as compared to a diesel-biodiesel blend (B8)

Biodiesel presents a higher degradability than petroleum hydrocarbons in soils. Since microorganisms dominate biodegradation processes, impacts on soil microbiota provide information regarding the course of fuel attenuation. We aimed to evaluate the effects of biodiesel (B100) and a diesel–biodiesel blend (B8) on soil microbial indicators. In microcosms, an oxisol was spiked with B100 (5% and 10%, w w-1 dry soil) or B8 (5% and 10%, w w-1 dry soil). In addition to microbial parameters, phytotoxicity, pH, and fuel attenuation were assessed during 90 days. Spiked soils exhibited increased cumulative respiration than non-contaminated controls; however, it was lower with B100 (140–204%) than with B8 (347–420%). Initial pH (6.0) slightly diminished with B8 after 90 days (~5.7), but decreased to ~3.9 after 30 days with B100. Heterotrophic and B8-degrading bacteria were 1.6–2.4 and 1.5–2.5 Log higher with B8 as compared to controls; conversely, heterotrophic and B100-degrading populations were reduced by B100 (3.5–4.5 and 4.7–6.8 Log lower than controls). B100 resulted in more prominent negative impacts on microbial biomass, metabolic quotient and soil enzyme activities. Phytotoxicity towards cucumber seeds tended to be mitigated in B8-5% soil, whereas the opposite has been observed with B100. Biodiesel fatty acid methyl esters (FAME) were completely (or highly) attenuated in B8 microcosms; nonetheless, in B100 soils, partial attenuation occurred only for unsaturated FAME. These findings are particularly discussed considering the prominent acidification in B100-spiked soils. In addition to B8, the results indicate that heavy soil contaminations with biodiesel pose significant environmental hazards.

Experimental investigation on the effect of compression ratio over emission and performance characteristics of the diesel engine using ternary blends

ABSTRACT A study of the existing literature on the effects of diethyl ether with different biodiesels such as Fish, Neem, Calophyllum Inophyllum, Cottonseed, and Soybean biodiesel was undertaken. Till date, no study related to the combined effects of repurpose used cooking oil biodiesel/diethyl ether/diesel blends and different compression ratios with different loading conditions has been reported in the literature. Moreover, the current study reveals that there are some major flaws in the existing scenario such as no reduction in harmful exhaust gases such as carbon dioxide, hydrocarbon, carbon monoxide, and nitrogen oxide. There is no noticeable improvement in the performance characteristics such as brake thermal efficiency and brake specific fuel consumption. This investigation has been carried out for controlling harmful emissions and improving the performance of the engine. The present study investigates the combined impact of compression ratios on emission and performance characteristics of a diesel engine using ternary blends in comparison with diesel. This study provides eco-friendly working conditions that result in fewer emissions with improved performance. The results show that a higher compression ratio is useful for minimizing nitrogen oxide emission, while a lower compression ratio is useful for minimizing carbon monoxide emission. CR16 works effectively with a higher proportion of diethyl ether (2.4 and 3.2%) and provides better results for minimizing emissions with improved performance. The following eco-friendly blends delivered lower emissions with improved performance. These blends are: A0.8_B19.2: CR16 and CR15; A1.6_B18.4: CR17 and CR16; A2.4_B17.6: CR16, CR15, and CR14; A3.2_B16.8: CR16 and CR15.

Passion fruit seed extract as an antioxidant additive for biodiesel; shelf life and consumption kinetics

One of the primary concerns in the use of biodiesel is its susceptibility towards radical-mediated oxidative reactions. The presence of unsaturated methyl esters renders biodiesel vulnerable to oxidation. It necessitates strategic interventions, which among a few others, includes the use of antioxidant additives. Natural antioxidants have multiple significant advantages over their synthetic counterparts. In the present study, the activity of methanolic passion fruit seed (PFS) extract as an antioxidant additive for waste cooking oil (soybean) biodiesel has been evaluated. The PFS extract contained a high proportion of phenolic compounds and exhibited excellent antiradical activity against model radical DPPH, which encouraged us to explore the case of unstable biodiesel further. At a concentration of 200 ppm, the PFS extract augmented the fuel's resistance towards oxidation to levels where it could comply with European and the Indian specifications for blend-stock biodiesel. The performance of PFS extract was comparable to that of synthetic antioxidants, including butylated hydroxyanisole and butylated hydroxytoluene. The present study substantiates the utility of plant extracts rich in phenolics as an antioxidant additive for biodiesel.